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Geting wrong coordinates with gluUnProject

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Hello!!! I have a problem with gluUnProject function. The code:
GLint viewport[4];								
GLdouble projection[16];							
GLdouble modelview[16];							
GLfloat winX, winY, winZ;							
GLdouble posX, posY,posZ,posZ1,posZ2;					

glGetIntegerv(GL_VIEWPORT, viewport);	
glGetDoublev(GL_PROJECTION_MATRIX, projection);		
glGetDoublev(GL_MODELVIEW_MATRIX, modelview);					

POINT mouse;
ScreenToClient(hwnd, &mouse);

winX = (float)mouse.x;					
winY = (float)mouse.y;					
winY = (float)viewport[3] - winY;		

glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
gluUnProject(winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);
The problem is, that the coordinates of axes that are on the plane of monitor (for example X and Y) are good, but the coordinate of perpendicular axis (f.e Z)is not 0 but fRange or -fRange. fRange in my code, is the clipping plane from glOrtho. When I Rotate the view for example Y rotation -90 or 90 degrees, the coordinate of perpendicular to monitor plane axis X is fRange/-fRange not 0. When I use an isometric view the (0,0,0) point is not in the centre of the coordinate system but somewhere far away. I solve the problem for Z coordinate:
gluUnProject(winX, winY, 0, modelview, projection, viewport, &posX, &posY, &posZ1);
gluUnProject(winX, winY, 1, modelview, projection, viewport, &posX, &posY, &posZ2);
And when I have Z1 and Z2 I can calculate the proper Z value. But what about rotations when my X or Y axis become a Z axis(perpendicular to monitor plane) then X and Y coordinates are not proper but fRange/-fRange (they are good only in front and back view). I don't have any idea what is wrong. Please help me. Thanks in advance!!! PS. Sorry for my bad English, I hope this post is understandable.

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